interim analysis of covid-19 cases in montana (as of 7/24 ... · golden valley judith basin...

Interim Epidemiological Analysis for Montana COVID-19 Cases as of 7/24/2020 1

Interim Analysis of COVID-19 cases in Montana (as of 7/24/2020) This report is an interim epidemiological review of COVID-19 cases in Montana. Data is analyzed based on information available as of July 24, 2020. Current case count at the time of analysis is:

Case Count = 3,252 This report is completed using data that is available during the time of analysis and there may be a delay between current case count and this report, due to rapidly changing updates. When data is limited to available information, number of cases included in analysis is indicated in graphs. Geographic Distribution There are 3,252 cases of COVID-19 reported in 50 counties in Montana. Most cases are reported in more populous counties. Yellowstone County and Gallatin County have been the most impacted, reporting 26% and 23% of all reported cases, respectively. Big Horn (7%), Missoula (6%), Flathead (5%), Lake (4%), Cascade (3%) and Lewis & Clark (3%) counties report more than 100 cases each (Figure 1). Figure 1: Map of Reported Montana COVID-19 cases*

*Cases reported on the map initially included residents of other states who were tested and isolated in Montana. As COVID-19 is now widespread across the United States, the map no longer includes out of state residents who test positive in Montana in order to align with CSTE residency guidelines that classify cases by the individual’s state of residence. This is standard practice for all communicable diseases to ensure accurate data for Montana.


Epidemiological Data A total of 3,252 cases were reported as of 7/24/2020. Illness onset date is available for most (62%) reported cases. When onset date is not available, collection date is used to calculate an estimated onset date (Figure 2). Illness onsets that occurred within the past 10 days may not yet be reported, due to a lag time between illness onset, seeking a provider to get tested, and receiving test results. Figure 2: Epi Curve for Montana COVID-19 cases

The first COVID-19 case in Montana was reported on 3/11/2020. Since then, new reports have climbed to 3,252 cases (Figure 3). Growth was initially exponential until reaching about 100 case reports, then growth became linear. By mid-April, growth significantly slowed down and during most of May there were few new reported cases. Since reaching 500 reported cases in early June, case reports have grown exponentially again. Of note, updated CDC contact tracing recommendations on May 29, 2020 may contribute to an increase in reported cases as all contacts to a case are recommended to be tested. Figure 3: Cumulative reported cases for COVID-19 in Montana

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COVID-19 Cases in Montana by Date of Report and Cumulative Total, 2020 [N=3,252]

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Data current as of 7/24/2020


Laboratory Data COVID-19 testing was initially available solely through the CDC. COVID-19 PCR testing capability was implemented by the Montana Public Health Laboratory (MTPHL) on March 9th. Private laboratories began implementing COVID-19 testing in the weeks following. Private laboratories include reference laboratories and those in smaller hospital labs performing point-of-care (POC) testing. A total of 151,029 tests have been completed to date. In July, an average of 17,000 tests were completed weekly, which is up by 66% of the number of specimens tested weekly in June (Figure 4).

Figure 4: Total Laboratory Testing for COVID-19 in Montana

So far 3,689 positive tests have been resulted through MTPHL and private laboratories. Some of these tests are repeat specimens from the same individual to check for clearance of the virus, but positive cases are only counted once. The overall positivity rate for all laboratory testing to date is about 2%, though this has varied over time. During the first peak in late March and early April, the weekly positivity reached over 4% and has dropped down to a low of 0.4% in May. In June, the average weekly positivity began to rise and is currently above 4% (Figure 5). Figure 5: Positive Laboratory Tests for COVID-19 in Montana

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Of all the COVID-19 tests conducted in Montana, most were from persons in Yellowstone County (14%), followed by Missoula (10%) and Cascade (10%) counties (Figure 6). Lab testing data is displayed for county of residence when known. When county of residence is unknown, the county of the facility collecting the test was used. Positive case reports are reflected in Figure 1 and are always counted by county of residence. Figure 6: COVID-19 Total Tests and Test Rate in Montana

COVID-19 Testing Rates and Total Test Performed by County – Montana, through 7/24/2020

The counties with the highest rate of tests per 1,000 residents are Glacier (518.4/1,000), Rosebud (372.9/1,000), Big Horn (282.8/1,000), Toole (281.0/1,000), Park (263.8/1,000), and Custer (261.4/1,000) counties (Figure 6 & 7). The average COVID testing rate for Montana is 140.3/1,000 population. Large scale community test events contribute to COVID testing rate by county. Figure 7: Ranked COVID Test Rate by County in Montana

Ranked COVID-19 Testing Rate per 1,000 Residents by County – Montana, through 7/24/2020

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Age and Demographic Distribution Persons between 20-29 years of age account for 28% of all reported COVID-19 cases in Montana. The next most common age group is 30-39 years (16%), followed by 40-49 and 50-59 years (12% each) (Figure 8). The median age for all cases is 35 years of age with a range between <1-98 years. Fifty percent of cases are between 24-56 years of age. Figure 8: Age Distribution for COVID-19 cases in Montana

In the eight counties with more than 100 reported cases, the age distribution shows some slight variations. Most of these counties report ages comparable to the state average, with Lewis & Clark County reporting a much higher median age of 48 years old and Gallatin County a much lower median age of 29 years old (Figure 9). Reported cases in Gallatin and Missoula Counties tend to be younger than cases in other counties. Figure 9: Age Distribution for COVID-19 cases in select Montana Counties

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Age Distribution among COVID-19 Patients in Montana [N=3,252]Data current as of 7/24/2020



Persons infected with COVID-19 are equally distributed among men and women, with 51% of cases reported as female and 49% reported as male. Of 2,381 (73%) cases with known race at the time of report, 81% of persons identify as white and 17% as American Indian, Alaska Native, Native Hawaiian or Pacific Islander. Other races, making up less than 3% of the cases, identify as African American, Asian or other race (Table 1). Ninety-four percent of all cases with ethnicity information available identify as non-Hispanic and 6% as Hispanic. Native Americans make up about 7% of Montana’s population, but represent 17% of reported COVID-19 cases in the state. Transmission Characteristics There are 50 counties reporting COVID-19 cases and of these, 27 indicate that at least one person acquired the virus in the community. Of current data available, about 41% of cases were contacts to a known case, either within the household or otherwise. Twenty-seven percent of new case reports were connected to a known cluster of cases, and 21% of cases with known transmission information likely acquired the virus in the community; most of those are in Gallatin and Yellowstone counties. Ten percent of reported cases likely acquired the virus through travel-related exposures (Figure 10). Figure 10: Known Routes of Transmission for Montana COVID-19

Cluster27%

Community acquired

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Contact24%

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Travel associated10%

Route of Transmission for COVID-19 cases in Montana, 2020 [N=1,815]

Data is currently under investigation for 1,437 (44%) persons.

Race Count Percent White 1,925 81% American Indian, Alaska Native, Native Hawaiian, Pacific Islander

395 17%

Black or African American

20 0.8%

Asian 9 0.4% Other 32 1.3% TOTAL 2,381

Table 1: Race of COVID-19 Cases in Montana


Transmission changes over time can indicate effective public health efforts, such as timely investigations, thorough contact findings, and measures to reduce community-acquired transmission. Transmission information is generally unknown for newly reported cases under investigation. Contact tracing and cluster investigations have significantly contributed to finding new cases, indicating that disease control efforts through local public health staff is identifying those infected and isolating them appropriately. No clusters were reported in early May, but new clusters have been identified towards the end of May and now increasingly contribute to new case reports. In July, clusters have added more than one quarter of the cases that month. Contacts and household contacts continue to be identified, making up nearly half of all cases reported in May through July. The percent of community-acquired cases has steadily contributed to disease counts until mid-April. After that, new community-acquired cases only contributed to new COVID-19 reports periodically, but with increased frequency in June and July. In July, about 1 out of 5 new COVID-19 cases was community-acquired. Travel-related transmission contributed to most cases early in the outbreak and then declined significantly, contributing only sporadically to new cases over time (Figure 11). Persons are more likely to acquire the virus through contact with a known case, especially within a household, or during a cluster investigation. Figure 11: Percent of known transmission contributing to COVID-19 Montana cases

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Transmission over Time for COVID-19 cases in Montana [N=1,815]

Community acquired Contact Cluster HAI Household contact Travel associated

Additional data will impact the findings during this time period.Data current as of 7/24/2020

CATEGORY DEFINITION

TRAVEL ASSOCIATED Case traveled out-of-state during the incubation period COMMUNITY ACQUIRED Case was unable to be linked with other known cases CONTACT Contact to a case not in their household and not part of a known cluster HOUSEHOLD CONTACT Household contact to a confirmed case CLUSTER Case is part of a known cluster HAI Healthcare-associated infection UNDER INVESTIGATION Likely route of transmission is still under investigation


More detail about route of transmission has been analyzed for the eight counties with more than 100 reported cases. Clusters contribute to about one third of all cases in Big Horn, Cascade and Yellowstone counties. Contact and household contact investigations significantly impact case counts in Lake and Lewis & Clark counties. Contacts also contribute to more than 40% of new cases in Big Horn and Flathead counties, and more than one third in Cascade, Gallatin, Missoula and Yellowstone counties. Gallatin County has most cases attributable to community-acquired transmission (31%), whereas about one quarter of new cases in Big Horn, Flathead and Yellowstone counties are community-acquired. Travel-associated transmissions account for around 20% of cases in Missoula County and nearly 30% of new cases in Flathead County (Figure 12). Of all other counties reporting less than 100 cases, nearly half are contacts or household contacts, and one third are part of clusters. About ten percent were either travel-related or acquired the virus in the community. Figure 12: Breakdown of known transmission for select counties

Outcomes The current outcomes of COVID-19 cases in Montana depict the impact of the illness on the population. There are currently 1,126 (35%) persons actively infected and 2,079 (64%) persons who have recovered, meaning they have cleared the illness and are released from isolation (Figure 13). Forty-seven persons, who were infected with COVID-19, have died. Counties reporting deaths include Yellowstone (22), Toole (6), Big Horn (5), Cascade, (2), Flathead (2), Sweet Grass (1), Ravalli (1), Missoula (1), Glacier (1), Rosebud (1), Gallatin (1), Lake (1), Madison (1), Lewis & Clark (1) and Lincoln (1). Persons who died were between 30 and 94 years of age, and 49% were male. For those who died, and race was known, 23 (68%) of them identified as white and 11 (32%) as Native American.

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Route of known Transmission by select county [N=1,289]

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Figure 13: Current infections and illness outcomes for Montana COVID-19

Figure 14 characterizes age distribution of those hospitalized due to COVID-19. Persons who required hospitalization for COVID-19 are generally much older than those not requiring hospitalization as indicated by the orange box. To date, 196 persons have been hospitalized with a median age of 66 years, half of them are between 54 and 78 years old (range: 23–94 years). Those who did not require hospitalization have a median age of 34, and half of patients are between 23 and 53 years old (range: 2–98 years). Twelve percent of Native Americans infected with COVID-19 required hospitalization versus seven percent of those who identify as white and were infected with COVID-19. Figure 14: Age Distribution among COVID-19 cases compared by known hospitalization status

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Total Reported Cases Recovered and released from isolation Deceased



Counties Reporting a COVID‐19 Case with Trendline

County 13‐Mar 20‐Mar 27‐Mar 3‐Apr 10‐Apr 17‐Apr 24‐Apr 1‐May 8‐May 15‐May 22‐May 29‐May 5‐Jun 12‐Jun 19‐Jun 26‐Jun 3‐Jul 10‐Jul 17‐Jul 24‐Jul Trend

Beaverhead 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 2 6 17

Big Horn 0 0 0 0 1 2 0 0 0 5 0 20 8 8 11 17 13 26 27 79

Blaine 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 3

Broadwater 1 0 1 2 0 0 0 0 0 0 0 0 0 0 0 1 0 3 1 0

Carbon 0 0 0 1 5 0 0 0 0 0 0 0 0 0 7 5 8 5 9 5

Cascade 0 0 7 4 2 0 1 1 1 1 0 0 0 0 4 6 7 13 21 42

Chouteau 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0

Custer 0 0 0 0 0 0 0 0 0 0 0 0 0 3 18 4 5 8 3 6

Daniels 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1

Dawson 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 7 0 0 0 2

Deer Lodge 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 1 2 2 6

Fallon 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1

Fergus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 2 0

Flathead 0 2 4 14 14 3 0 0 0 0 0 0 0 0 8 8 10 4 45 62

Gallatin 1 3 42 55 34 7 4 0 3 0 0 2 10 26 17 35 49 115 160 197

Garfield 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 10 2

Glacier 0 0 0 1 2 1 0 2 0 0 0 0 0 0 1 1 14 6 6 17

Golden Valley 0 0 0 0 1 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Granite 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 0 0

Hill 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 12 18 8

Jefferson 0 0 2 0 0 0 0 0 0 1 0 0 0 0 0 0 0 3 8 4

Judith Basin 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1

Lake 1 0 1 3 0 0 0 0 0 0 0 0 0 4 1 2 7 29 52 36

Lewis and Clark 0 3 6 4 3 0 0 0 0 0 0 0 2 1 3 3 6 13 33 24

Liberty 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Lincoln 0 0 3 3 1 0 0 0 0 0 0 0 0 0 0 0 2 4 31 9

Madison 0 1 2 3 2 0 0 0 0 0 0 0 0 0 0 0 7 12 16 15

McCone 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1

Meagher 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 0 0

Missoula 0 4 5 9 11 6 4 0 0 0 0 0 0 0 9 18 40 17 37 44

Musselshell 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Park 0 0 1 5 1 0 0 1 0 0 0 0 0 0 0 1 4 3 14 10

Pondera 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 3 3

Powder River 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1

Ravalli 0 1 0 1 1 2 0 0 0 0 8 0 1 1 2 5 11 9 8 1

Richland 0 0 0 0 3 0 0 0 0 0 0 0 0 0 3 4 9 9 6 7

Roosevelt 0 1 0 0 2 3 1 0 0 0 0 0 0 0 0 0 0 1 0 1

Rosebud 0 0 0 0 0 0 0 0 0 0 0 1 0 0 6 2 1 2 4 3

Sanders 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 3

Sheridan 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1

Silver Bow 1 0 8 2 0 0 0 0 0 0 0 0 0 0 0 2 6 5 6 5

Stillwater 0 0 0 0 1 0 0 0 0 0 0 0 0 1 1 1 2 3 4 3

Sweet Grass 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2

Teton 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 10 4 1 0

Toole 0 0 4 8 8 9 0 0 0 0 0 0 0 0 2 0 0 0 0 0

Treasure 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0

Valley 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 3 0 0 3

Wheatland 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0

Wibaux 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0

Yellowstone 1 4 18 15 19 13 7 4 1 3 3 2 14 4 12 29 97 188 246 162

MONTANA 5 19 107 135 111 49 19 8 5 10 11 25 35 48 109 155 316 504 794 787

MARCH 31, 2020

cumulative cases reported

counties

21022

MONTANA COVID-19 CASES

APRIL 30, 2020


counties

45227

MAY 31, 2020


counties

50530

JUNE 30, 2020


counties

1,01637


WEEK ENDING 7/3


counties

1,16739

WEEK ENDING 7/10


counties

1,67539

WEEK ENDING 7/17


counties

2,46546

WEEK ENDING 7/24


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3,25250

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COVID-19 Case Rates Per 100,000 Population - Montana and neighboring states, July 24, 2020

Case counts based on CDC case reports as of July 24, 2020 and 2019 population estimates from the U.S. Census Bureau

State Cases Reported

Idaho 18177

Montana 3252

North Dakota 5986

South Dakota 8395

Wyoming 2475


Recovered COVID-19 Cases -- Montana, July 24, 2020

46Counties:

1-665Range:

34Counties:

1-442Range:

Active COVID-19 includes cases who are hospitalized or recovering but still remain in isolation.

Recovered COVID-19 includes cases who have recovered and are released from isolation.


2,088Recovered:

1,117Active:

COVID-19 Cases by Report Date -- June 27- July 10, 2020

25Counties:

1-97Range:

316Cases:

Active COVID-19 Cases -- Montana, July 24, 2020

COVID-19 Cases by Report Date -- July 11- 24, 2020

42Counties:

1-408Range:

1,581Cases:

interim analysis of covid-19 cases in montana (as of 7/24 ... · golden valley judith basin...

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